类钙钛矿新铌酸盐Ba_6LaTi_3Nb_3O_(21)的合成、结构与介电特性  

Synthesis,Structure and Dielectric Properties of A New Pervoskite-related Niobate Ba_6LaTi_3Nb_3O_(21)

作　　者：张辉[1] 黄涛华[1] 方亮[1] 孟范成[1] 刘韩星[1] 袁润章[1] 

机构地区：[1]武汉理工大学材料复合新技术国家重点实验室,武汉430070

出　　处：《无机化学学报》2004年第4期426-428,共3页Chinese Journal of Inorganic Chemistry

基　　金：国家自然科学基金(No.50002007);教育部重大项目(No.0201);国际衍射数据中心(ICDD)Grant鄄in鄄Aid基金(No.02鄄05;02鄄40)资助项目。

摘　　要：A New Niobate Ba 6 LaTi 3 Nb 3 O 21 was synthesized by high temperature solid state reaction in the BaO - La 2 O 3 - TiO 2 - Nb 2 O 5 system.The chemical compositions,crystal structure,microstructure,density and melting point of the new compound were characterized by EPMA,XRD,DTA and so on.Ba 6 LaTi 3 Nb 3 O 21 crystallizes the rhombohedral system with unit cell parameters a=0.57388(2)nm,c=4.9283(3)nm,and space group R3m,Z=3.The structure may be described as six(Nb,Ti)O 6 octahedra corner - sharing along c - axis to form perovskite layer connected by Ba atoms.The Ba 6 LaTi 3 Nb 3 O 21 ceramics exhibits high dielectric of74.1,low dielectric loss of4.7 × 10 -4 and small temperature coefficient of dielectric constant of-69ppm · K -1 at1MHz due to its close structure and relative high dielectric polarizabilities of Ba 2+ ,La 3+ ,Ti 4+ and Nb 5+ .Ba 6 LaTi 3 Nb 3 O 21 might be a suitable candidate of highε r mi - crowave dielectric ceramics.A New Niobate Ba 6 LaTi 3 Nb 3 O 21 was synthesized by high temperature solid state reaction in the BaO - La 2 O 3 - TiO 2 - Nb 2 O 5 system.The chemical compositions,crystal structure,microstructure,density and melting point of the new compound were characterized by EPMA,XRD,DTA and so on.Ba 6 LaTi 3 Nb 3 O 21 crystallizes the rhombohedral system with unit cell parameters a=0.57388(2)nm,c=4.9283(3)nm,and space group R3m,Z=3.The structure may be described as six(Nb,Ti)O 6 octahedra corner - sharing along c - axis to form perovskite layer connected by Ba atoms.The Ba 6 LaTi 3 Nb 3 O 21 ceramics exhibits high dielectric of74.1,low dielectric loss of4.7 × 10 -4 and small temperature coefficient of dielectric constant of-69ppm · K -1 at1MHz due to its close structure and relative high dielectric polarizabilities of Ba 2+ ,La 3+ ,Ti 4+ and Nb 5+ .Ba 6 LaTi 3 Nb 3 O 21 might be a suitable candidate of highε r mi - crowave dielectric ceramics.

关 键 词：类钙钛矿结构 铌酸盐 Ba6LaTi3Nb3O21 合成 结构 介电特性 微波介电陶瓷材料 固相反应 

分 类 号：TM21[一般工业技术—材料科学与工程] TM28[电气工程—电工理论与新技术]